Energy Flashcards
What are the 9 main types of energy?
thermal, GPE, elastic, kinetic, nuclear, electrostatic, chemical, magnetic, light
What are the 4 ways energy can be transferred?
mechanically, heating, electrically, radiation
What is a system?
the collection of matter of an object or multiple objects
What is the difference between an open and closed system?
in a closed system, neither matter or energy can leave or enter from the ‘outside’. in an open system it can
What is work done?
energy transferred
what are the 2 types of work done?
mechanical and electrical
Is the energy stored in a battery stored in its kinetic, or chemical energy store?
Chemical
Energy is transferred to a light bulb electrically.
How is energy transferred away from a light bulb?
thermal energy and light energy
What is the law of conservation of energy?
Energy cannot be created or destroyed. It can only be transferred from one form to another.
Which energy store increases when an object is lifted 1.5 m above the ground?
GPE`
What is kinetic energy of an object?
energy it possesses due to its motion
How do you work out kinetic energy?
1/2 * mass * velocity^2
mass in kg
velocity in m/s
An object has a mass of 2 kg, and is travelling at a velocity of 5 m/s.
How much kinetic energy does the object have?
25J
A cyclist is riding down a hill at a speed of 10 m/s.
The cyclist has 4 kJ of kinetic energy.
Calculate the cyclist’s mass.
80Kg
What is the gravitational field?
the area around an object which has gravity
What is earth’s gravitational field strength/
9.8 N/Kg
How do you calculate an objects weight?
mass * Gravitational field strength
What is the units of weight?
Newtons
What is the formula for GPE?
mass * GFS * height
mass is in Kg
GFS is in N/kg (usually 9.8)
height is in m
What is the weight of a 70 kg object on earth?
686 N
Tony has a mass of 65 kg on Earth. What is Tony’s mass on the moon?
65Kg
Which two factors determine the strength of the gravitational force of attraction?
The mass of the objects
The distance between the objects
A ball is thrown vertically upwards.
Which of the following shows the correct energy stores for the ball at the highest point.
GPE = maximum and KE = minimum
What is the internal energy of an object?
the total energy stored by the particles making up a substance or system
What is specific heat capacity?
amount of energy needed to heat 1 kg of a substance by 1 degree Celsius
What is the equation for change in internal energy using specific heat capacity?
change in energy = mass (kg) * S.H.C (j/kgC) * change in temp (C)
what is the specific heat capacity of water?
4200 J/kgC
A material with a higher specific heat capacity requires:
More energy to change its temperature
What happens to ‘dissipated’ energy?
It is lost to the surroundings
Conduction primarily takes place in:
solids
How does conduction work?
as one part of the solid is heated, the particles gain kinetic energy and vibrate faster causing them to collide into neighbouring particles. Through collisions the kinetic energy spreads through the solid, increasing the total thermal energy.
Which type of materials have a higher thermal conductivity?
metals
In what state of matter can convection take place in?
gases and liquids
what is a convection current?
gas or liquid is heated, causing it to gain kinetic energy and become less dense. This means it rises above the other, less dense, colder particles. It then cools and sinks again, whilst the once cold particles were heated and rise
What type of radiation is heat energy?
infrared
What are3 features of a house which help to reduce heat loss by conduction?
Double glazed windows
Walls made of a material with low thermal conductivity
Cavity walls
What helps to reduce friction between two surfaces?
lubricant
What is the formula for power?
energy or work done / time
What are the units of power?
Watts (W)
A 25 W light bulb was turned on and consumed 650 J of energy before it was turned off. How long was the light bulb on for?
26s
A toaster consumes 45,000 J in 45 s, what is its power consumption?
1000W
How could a bicycle be made more efficient?
Add some oil to the chain
The government has recommended that the sale of filament lamps should be banned. suggest why.
Filament lamps are inefficient
During the course of a day, an electric motor usefully transfers 1600 kJ. The energy supplied to the electric motor is 4000 kJ
What is the efficiency of the motor?
0.4
The efficiency of a 25 W energy-saving lamp is 0.6.
How much energy does it waste each second?
10J
A speaker has an input power of 30 W, but only 10 W is converted to sound energy.
Suggest what happens to the other 20 W.
lost as thermal energy
What are the 2 types of energy resources?
renewable and non-renewable
What are 5 of the main renewable energy resources?
Wind
Solar
Geothermal
Water waves
Biofuels
Hydroelectricity
Tidal
what are the 3 fossil fuels?
coal, crude oil, natural gas
Is nuclear energy renewable?
no
Which type of energy resource provides the majority of our electricity?
Non-renewable energy resources
Which of the energy resources below is the most widely used for heating homes in the UK?
natural gas
Which of the following can be mixed with petrol to make it more environmentally friendly?
biofuel
What are fossil fuels?
hydrocarbon-containing materials formed naturally in the earth’s crust from the remains of dead plants and animals.
How long does it take for fossil fuels to form?
millions of years
What are 3 pros of fossil fuels?
cheap
can be used in any condition
much of our current infrastructure is designed to run using fossil fuels
What are 3 cons of fossil fuels?
they are a limited resource, so will run out one day
they produce carbon dioxide when burned
they sometimes produce toxic gases when burned
What are 3 pros of nuclear power?
do not produce pollutants
can be used in any condition
very unlikely to run out
what are 3 cons of nuclear power?
technically a finite resource
produces radioactive waste
quite expensive
nuclear meltdown
What are 2 pros of solar and wind power?
they dont produce pollutants while operating
they have low running costs
What are 3 cons of solar and wind power?
highly dependant on weather
relatively high upfront costs
take up a lot of land space
How do geothermal power stations work?
1)cold water is pumped into the ground with lots of volcanic activity as it is often hot
2) the water heats up and can be pumped back up to be used in homes
3) we can let the water heat up so much it becomes steam which then spins a turbine
4) the generator can then produce electricity
What are the main disadvantages of geothermal energy?
They can be expensive to build
They can only be built in certain areas of the world
What are biofuels?
organic materials which can generate electricity or be burned for heat
What are the advantages of biofuels?
They’re renewable
They’re easy to transport
They can be used in cars
What are the disadvantages of biofuels?
They require a lot of energy to harvest, process and transport
They require a large area of land to grow
What do we mean when we say that ‘biofuels are carbon neutral’?
They absorb the same amount of carbon dioxide while growing, as they release when they’re burned
In theory biofuels should be carbon neutral, but in reality they are not.
Why is this?
In order to grow the biofuels, we often have to clear land by cutting down trees. This means the trees can no longer photosynthesise and absorb CO2 themselves, and will also release large amounts of CO2 if burned.
In addition, it usually requires a lot of energy to harvest, process, and transport the biofuels, which itself will produce a lot of CO2.
How do hydroelectric dams work?
As water flows downhill (e.g. from mountains), a hydroelectric dam will trap the water in a man made lake, which is also known as a reservoir.
Then whenever water is released through the dam, it spins turbines which are connected to generators, and so produce electricity.
The water can then return to the river on the downstream side of the dam.
Which energy transfer takes place as water flows from the higher side of a hydroelectric dam (or tidal barrage) to the lower side?
Gravitational potential energy ➔ kinetic energy
What are the advantages of hydroelectric dams?
Higher electricity demands can be met by increasing water flow
They are a source of renewable energy
What are the disadvantages of hydroelectric dams and tidal barrages?
Upfront building costs are quite high
They can flood land upstream
What are 2 pros and 2 cons of wave power?
renewable and no harmful polluting gases are produced
difficult to scale up the designs for wave machines to produce more electricity and having many wave machines can negatively impact wildlife
